The present invention relates to a method of preparing metallic additives of high alkalinity useful in improving the detergent and dispersant properties of lubricating oils, and additives produced by such method.
It is known to add various compounds to lubricating oils to improve the properties of such oils. U.S. Pat. No. 4,251,379 discloses a high alkalinity additive for lubricating oils prepared by first sulfurizing an alkylphenol in the presence of an alkylbenzene sulfonate of low or zero Total Basic Number (T.B.N.), an alkaline earth base, and an alkylene glycol, precarbonating the mixture thus obtained, super-alkalinizing and carbonating the resultant precarbonated mixture by means of an alkaline earth base, CO.sub.2, and an alkylene glycol, and eliminating the excess alkylene glycol.
U.S. Pat. No. 4,382,004 discloses magnesium alkylphenates useful as additives for lubricating oils obtained by preparing a suspension of active magnesium oxide in methanol, contacting the suspension with a mixture containing an alkylphenol bearing one or more C.sub.6 -C.sub.60 alkyl substituents, a dilution oil, and optionally, a heavy alcohol having a boiling point between 100.degree. and 200.degree. C., the ratio or number of moles of active magnesium oxide to number of recurrent phenolic OH units being between about 0.25 and 2, and carbonating the resultant medium under pressure with carbon dioxide.